Frequencies for first 10,000 rows of unkpay variable in namcs1994 dataset :

   expected |
  source of |
  payment - |
    unknown |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,838       98.38       98.38
          1 |        162        1.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016